If you def want Nav as an option, look at getting a Google Nexus 7. I built a custom mount for it that holds it on the front of the dashboard.
Works pretty flawlessly.
I'll post a few pictures of it once I get a chance.
Montego Blue Metallic e92 6MT
|| BMW Performance SSK Kit || Charcoal Delete w/ K&N Drop-In || CDV Delete || Custom Clutch Stop || (3) Stage Manifold Swap || Stage 2 Eurocharged Tune (